U.S. patent application number 13/061290 was filed with the patent office on 2011-06-30 for process for removing hydrogen sulfide in crude oil.
Invention is credited to Alan E. Goliaszewski, Lawrence John Karas.
Application Number | 20110155646 13/061290 |
Document ID | / |
Family ID | 41797347 |
Filed Date | 2011-06-30 |
United States Patent
Application |
20110155646 |
Kind Code |
A1 |
Karas; Lawrence John ; et
al. |
June 30, 2011 |
PROCESS FOR REMOVING HYDROGEN SULFIDE IN CRUDE OIL
Abstract
A method for reducing the amount of hydrogen sulfide present in
crude oil includes adding a hydrogen sulfide scavenger composition
to the crude oil to capture the hydrogen sulfide, migrating the
captured sulfides to an aqueous phase and removing the aqueous
phase from the crude oil. The hydrogen sulfide scavenger
composition includes glyoxal and a quaternary ammonium salt.
Inventors: |
Karas; Lawrence John;
(Spring, TX) ; Goliaszewski; Alan E.; (Hockessin,
DE) |
Family ID: |
41797347 |
Appl. No.: |
13/061290 |
Filed: |
September 2, 2008 |
PCT Filed: |
September 2, 2008 |
PCT NO: |
PCT/US08/75030 |
371 Date: |
February 28, 2011 |
Current U.S.
Class: |
208/187 |
Current CPC
Class: |
C10G 29/20 20130101 |
Class at
Publication: |
208/187 |
International
Class: |
C10G 33/00 20060101
C10G033/00 |
Claims
1. A method for reducing the amount of hydrogen sulfide present in
crude oil comprising adding a hydrogen sulfide scavenger
composition to the crude oil to capture the hydrogen sulfide,
migrating the captured sulfides to an aqueous phase and removing
the aqueous phase from the crude oil, wherein the hydrogen sulfide
scavenger composition comprises glyoxal and a quaternary ammonium
salt.
2. The method of claim 1 wherein the scavenger composition is added
to the crude oil in an amount of from about 1 ppm by weight to
about 3000 ppm by weight, based on the weight of the crude oil.
3. The method of claim 1 wherein the scavenger composition is added
to the crude oil in an amount of from about 10 ppm by weight to
about 2000 ppm by weight, based on the weight of the crude oil.
4. The method of claim 1 wherein the catalyst has formula I:
R.sub.1R.sub.2R.sub.3R.sub.4N.sup.+X.sup.- I wherein R.sub.1,
R.sub.2, R.sub.3 and R.sub.4 are each independently an alkyl group
having from 1 to 30 carbon atoms, an aryl group having from 6 to 30
carbon atoms or an arylalkyl group having from 7 to 30 carbon
atoms; and X is a halide, sulfate, nitrate or carboxylate.
5. The method of claim 4 wherein the alkyl group is selected from
the group consisting of methyl, ethyl, propyl, isopropyl, butyl,
isobutyl, pentyl, hexyl, decyl and dodecyl.
6. The method of claim 4 wherein the aryl group is phenyl.
7. The method of claim 4 wherein the arylalkyl group is benzyl.
8. The method of claim 4 wherein the halide is selected from the
group consisting of chloride, bromide and iodide.
9. The method of claim 1 wherein the catalyst is alkyl benzyl
ammonium chloride or benzyl cocoalkyl (C.sub.12-C.sub.18)
dimethylammonium chloride.
10. The method of claim 1 wherein the catalyst is selected from the
group consisting of dicocoalkyl (C.sub.12-C.sub.18)
dimethylammonium chloride, benzyl cocoalkyl (C.sub.12-C.sub.18)
dimethylammonium chloride, ditallowdimethylammonium chloride,
di(hydrogenated tallow alkyl) dimethyl quaternary ammonium methyl
chloride, methyl bis(2-hydroxyethyl cocoalkyl (C.sub.12-C.sub.18)
quaternary ammonium chloride, dimethyl(2-ethyl) tallow ammonium
methyl sulfate, n-dodecylbenzyldimethylammonium chloride,
n-octadecylbenzyldimethyl ammonium chloride,
n-dodecyltrimethylammonium sulfate, soya alkyltrimethylammonium
chloride and hydrogenated tallow alkyl (2-ethylhyexyl) dimethyl
quaternary ammonium methylsulfate.
11. The method of claim 1 wherein the quaternary ammonium salt is
present from about 0.01 percent by weight to about 15 percent by
weight based on the weight of the glyoxal.
12. The method of claim 11 wherein the quaternary ammonium salt is
present from about 1 percent by weight to about 10 percent by
weight, based on the weight of the glyoxal.
13. The method of claim 1 wherein the crude oil is treated in a
desalter.
14. The method of claim 13 wherein a water wash is added to the
crude oil.
15. The method of claim 14, wherein the water wash is added in an
amount of from about 1 percent by volume to about 50 percent by
volume based on the volume of the emulsion.
16. The method of claim 14 wherein the water wash is added in an
amount of from about 1 percent by volume to about 25 percent by
volume of the emulsion.
17. The method claim 14 wherein the water wash and crude oil are
emulsified by heating and mixing the crude oil and water wash.
18. The method of claim 14 wherein the crude oil and water wash are
heated to a temperature in a range of from about 90.degree. C. to
about 150.degree. C.
19. The method of claim 14 wherein the wash water is removed by
draining.
Description
FIELD OF THE INVENTION
[0001] This invention relates generally to methods for removing
hydrogen sulfide and more particularly, to removing hydrogen
sulfide from crude oil.
BACKGROUND OF THE INVENTION
[0002] Crude oil may contain hydrogen sulfide, which is highly
corrosive in the presence of water and poisonous in very small
concentrations. The risk of exposure to hydrogen sulfide from
handling crude oil is a health and safety concern during storage,
transportation (shipping, truck or pipeline) and processing of the
crude oil.
[0003] Hydrogen sulfide scavengers are used to remove hydrogen
sulfide from the crude oil. Typical hydrogen sulfide scavengers are
triazines and aldehydes. However, triazines release amines into the
liquid hydrocarbon media and residual triazines thermally decompose
to release additional amines into the liquid hydrocarbon media and
may pose additional health concerns. The free amines can form
salts, which deposit on the processing equipment and cause
corrosion. Aldehydes can have slower reaction kinetics and may have
incomplete hydrogen sulfide scavenging.
[0004] What is needed is an improved scavenger for removing
hydrogen sulfide from crude oil.
BRIEF DESCRIPTION OF THE INVENTION
[0005] In one embodiment, a method for reducing the amount of
hydrogen sulfide present in crude oil includes adding a hydrogen
sulfide scavenger composition to the crude oil to capture the
hydrogen sulfide, migrating the captured sulfides to an aqueous
phase and removing the aqueous phase from the crude oil, wherein
the hydrogen sulfide scavenger composition includes glyoxal and a
quaternary ammonium salt.
[0006] The various embodiments provide an improved hydrogen
scavenging process for crude oil that quickly captures hydrogen
sulfide and does not generate amine byproducts.
DETAILED DESCRIPTION OF THE INVENTION
[0007] The singular forms "a," "an" and "the" include plural
referents unless the context clearly dictates otherwise. The
endpoints of all ranges reciting the same characteristic are
independently combinable and inclusive of the recited endpoint. All
references are incorporated herein by reference.
[0008] The modifier "about" used in connection with a quantity is
inclusive of the stated value and has the meaning dictated by the
context (e.g., includes the tolerance ranges associated with
measurement of the particular quantity).
[0009] "Optional" or "optionally" means that the subsequently
described event or circumstance may or may not occur, or that the
subsequently identified material may or may not be present, and
that the description includes instances where the event or
circumstance occurs or where the material is present, and instances
where the event or circumstance does not occur or the material is
not present.
[0010] In one embodiment, a method for reducing the amount of
hydrogen sulfide present in crude oil includes adding a hydrogen
sulfide scavenger composition to the crude oil to capture the
hydrogen sulfide, migrating the captured sulfides to an aqueous
phase and removing the aqueous phase from the crude oil, wherein
the hydrogen sulfide scavenger composition includes glyoxal and a
quaternary ammonium salt.
[0011] The crude oil may be any type of crude oil containing
hydrogen sulfide. Any amount of hydrogen sulfide the crude oil may
be reduced and the actual amount of residual hydrogen sulfide will
vary depending on the starting amount. In one embodiment, the
hydrogen sulfide levels are reduced to 150 ppm by weight or less,
as measured in the vapor phase, based on the weight of the crude
oil. In another embodiment, the hydrogen sulfide levels are reduced
to 100 ppm by weight or less, as measured in the vapor phase, based
on the weight of the crude oil. In another embodiment, the hydrogen
sulfide levels are reduced to 50 ppm by weight or less, as measured
in the vapor phase, based on the weight of the crude oil. In
another embodiment, the hydrogen sulfide levels are reduced to 20
ppm by weight or less, as measured in the vapor phase, based on the
weight of the crude oil.
[0012] The hydrogen sulfide scavenger composition is added to the
crude oil in any conventional manner. In one embodiment, the
scavenger composition is injected into the crude oil by a
conventional in-line injection system and may be injected at any
point in-line suitable to allow the scavenger to mix with the crude
oil, such as in a pipeline or in a tanker. The scavenger
composition can be added to the crude oil in a continuous manner or
can be added in one or more batch modes and repeated additions may
be made.
[0013] The scavenger composition is added to the crude oil in any
amount sufficient to reduce the levels of hydrogen sulfide in the
crude oil. In one embodiment, the scavenger composition is added in
an amount of from about 1 ppm to about 3000 ppm by weight, based on
thew eight of the crude oil. In another embodiment, the scavenger
composition is added in an amount of from about 10 ppm by weight to
about 2000 ppm by weight, based on the weight of the crude oil. In
another embodiment, the scavenger composition is added in an amount
of from about 50 ppm by weight to about 1500 ppm by weight, based
on the weight of the crude oil. In another embodiment, the
scavenger composition is added in an amount of from about 100 ppm
by weight to about 1200 ppm by weight, based on the weight of the
crude oil.
[0014] The hydrogen sulfide scavenger may be added neat or diluted
with water or solvent and may be formulated or blended with other
suitable materials or additives.
[0015] The hydrogen sulfide scavenger composition captures and
neutralizes hydrogen sulfide in the crude oil by incorporating the
sulfur into an inert ringed compound. The ringed compound is
non-hazardous and is attracted to a water phase and migrates to a
water phase away from an oil phase.
[0016] The hydrogen sulfide scavenger composition comprises glyoxal
and a quaternary ammonium compound. Glyoxal is a water-soluble
aldehyde and may include oligomers of glyoxal. Glyoxal is
commercially available. The glyoxal is catalyzed with a quaternary
ammonium salt, which improves the efficacy of the scavenger
composition and enhances removal of hydrogen sulfide. The catalyst
may be any suitable quaternary ammonium salt. In one embodiment,
the catalyst has formula I:
R.sub.1R.sub.2R.sub.3R.sub.4N.sup.+X.sup.- I
wherein R.sub.1, R.sub.3 and R.sub.4 are each independently an
alkyl group having from 1 to 30 carbon atoms, an aryl group having
from 6 to 30 carbon atoms or an arylalkyl group having from 7 to 30
carbon atoms; and X is a halide, sulfate, nitrate or carboxylate.
The alkyl groups and the aryl groups may be substituted or
unsubstituted.
[0017] In one embodiment, R.sup.1 is an alkyl group having from 1
to 24 carbon atoms. In one embodiment, R.sup.2 is an alkyl having
from 1 to 24 carbon atoms, an aryl group having from 6 to 24 carbon
atoms or an arylalkyl group having from 7 to 24 carbon atoms.
[0018] In one embodiment, R.sup.3 and R.sup.4 are each,
independently, an alkyl group having from 1 to 24 carbon atoms. In
another embodiment, R.sup.3 and R.sup.4 are each, independently, an
alkyl group having from 1 to 4 carbon atoms.
[0019] The alkyl group includes, but is not limited to, methyl,
ethyl, propyl, isopropyl, butyl, isobutyl, pentyl, decyl or
dodecyl. The aryl group may be phenyl. The arylalkyl group include
may be benzyl. The halide may be chloride, bromide or iodide. The
sulfite may be a methyl sulfate. The nitrate may be a bisulfate
nitrate. The carboxylate may be acetate.
[0020] In one embodiment, the quaternary ammonium salt is alkyl
benzyl ammonium chloride or benzyl cocoalkyl (C.sub.12-C.sub.18)
dimethylammonium chloride. In another embodiment, the quaternary
ammonium salt includes, but is not limited to dicocoalkyl
(C.sub.12-C.sub.18) dimethylammonium chloride,
ditallowedimethylammonium chloride, di(hydrogenated tallow alkyl)
dimethyl quaternary ammonium methyl chloride, methyl
bis(2-hydroxyethyl cocoalkyl (C.sub.12-C.sub.18) quaternary
ammonium chloride, dimethyl(2-ethyl) tallow ammonium methyl
sulfite, n-dodecylbenzyldimethylammonium chloride,
n-octadecylbenzyldimethyl ammonium chloride,
n-dodecyltrimethylammonium sulfate, soya alkyltrimethylammonium
chloride or hydrogenated tallow alkyl (2-ethylhyexyl) dimethyl
quaternary ammonium methylsulfate.
[0021] In one embodiment, the quaternary ammonium salt is present
from about 0.01 to about 15 percent by weight based on the amount
of glyoxal. In another embodiment, the quaternary ammonium salt is
present from about 1 to about 10 percent by weight based on the
amount of glyoxal.
[0022] The scavenger composition is attracted to an aqueous phase
and the captured sulfides will migrate into an aqueous phase. If an
emulsion is present, the captured sulfides can be migrated into the
aqueous phase from the crude oil and removed with the aqueous
phase. If no emulsion is present, a water wash can be added to
attract the captured sulfides. In one embodiment, the hydrogen
sulfide scavenger composition is added before the crude oil is
treated in a desalter, which emulsifies the hydrocarbon media with
a water wash to extract water soluble contaminants and separates
and removes the water phase from the crude oil.
[0023] In one embodiment, a water wash is added in an amount
suitable for forming an emulsion with the crude oil. In another
embodiment, the water wash is added in an amount of from about 1 to
about 50 percent by volume based on the volume of the emulsion. In
another embodiment, the wash water is added in an amount of from
about 1 to about 25 percent by volume based on the volume of the
emulsion. In another embodiment, the wash water is added in an
amount of from about 1 to about 10 percent by volume based on the
volume of the emulsion. In one embodiment, the amount of crude oil
is present in an amount of front about 50 to about 99 percent by
volume based on the volume of the emulsion. In another embodiment,
the crude oil is present in an amount of from about 75 to about 99
percent by volume based on the volume of the emulsion. In another
embodiment, the crude oil is present in an amount of from about 90
to about 99 percent by volume based on the volume of the
emulsion.
[0024] The water wash and crude oil are emulsified by any
conventional manner. In one embodiment, the water wash and crude
oil are heated and thoroughly mixed to produce an oil-in-water
emulsion. In one embodiment, the water wash and crude oil are
heated at a temperature in a range of from about 90.degree. C. to
about 150.degree. C. The water wash and crude oil are mixed in any
conventional manner, such as an in-line static mixer or an in-line
mix valve with a pressure drop of about 0.2 to about 2 bar
depending on the density of the crude oil. The emulsion is allowed
to separate, such as by settling, into an aqueous phase and an oil
phase. In one embodiment, the aqueous phase is removed. In another
embodiment, the aqueous phase is removed by draining the aqueous
phase.
[0025] Demulsifiers may be added to aid in separating the water
from the crude oil. In one embodiment, the demulsifiers include,
but are not limited to, oxyalkylated organic compounds, anionic
surfactants, nonionic surfactants or mixtures of these materials.
The oxyalkylated organic compounds include, but are not limited to,
phenolformaldehyde resin ethoxylates, alkoxylated polyols and
amities, such as Pluronic.RTM. block co-polymers. The anionic
surfactants include alkyl or aryl sulfonates, such as
dodecylbenzenesulfonate. These demulsifiers may be added in amounts
to contact the water from about 1 to about 1000 ppm by weight based
on the weight of the crude oil. Combinations of additives may be
used, but the total amounts of additives added should be in the
range of from about 1 to about 1000 ppm by weight based on the
weight of the crude oil.
[0026] In order that those skilled in the art will be better able
to practice the present disclosure, the following examples are
given by way of illustration and not by way of limitation.
EXAMPLES
Example 1
[0027] Hydrogen sulfide scavenging tests were performed on a crude
oil containing 500 ppm hydrogen sulfide in the liquid phase from a
Texas refinery in Valero. Testing was performed using the modified
ASTM 5705-95 test that measures vapor phase H.sub.2S two hours
after treatment (140.degree. F.) via dragger tube. Results are
shown in Table 1.
TABLE-US-00001 TABLE 1 H.sub.2S Scavenger Sample (1000 ppm)
Residual H.sub.2S (ppm) CE-1 MEA.sup.1 triazine 400 CE-2 Triazine
8411C.sup.2 120 CE-3 MMA.sup.3 triazine + Catalyst.sup.4 200 CE-4
MEA.sup.1 triazine + Catalyst.sup.4 200 CE-5 Glyoxal 950 1 Glyoxal
+ Catalyst.sup.4 140 .sup.1MEA is monoethanol amine .sup.2Triazine
8411C is available commercially from Clearwater, Inc as Sulfa-Clear
8411C. .sup.3MMA is monomethyl amine .sup.4Catalyst is
cocoalkyldimethylbenzyl ammonium chloride (Arquad .RTM. DMCB-80) at
1.6% by weight treatment level (actives basis) based on the weight
of the triazine or glyoxal.
[0028] Sample 1 has comparable results to the use of a triazine in
reducing hydrogen sulfide, but the catalyzed glyoxal can be removed
in an aqueous phase; whereas, the triazine remains with the oil and
can generate amines upon further processing. The catalyzed glyoxal
sample shows significant improvement over glyoxal; whereas,
catalyzing the triazine does not improve the performance of the
triazine.
Example 2
[0029] The concentration of the hydrogen sulfide in the vapor phase
was determined at different levels of treatment dosages after 1
hour and 2 hours for samples 1 and comparative examples CE-1 and
CE-3, as shown in Table 2.
TABLE-US-00002 TABLE 2 CE-1 CE-3 Sample 1 CE-1 CE-3 Sample 1
Dosages H.sub.2S level H.sub.2S level H.sub.2S level H.sub.2S level
H.sub.2S level H.sub.2S level (ppm) (ppm) @ 1 hour (ppm) @ 1 hour
(ppm) @ 1 hour (ppm) @ 2 hours (ppm) @ 2 hours (ppm) @ 2 hours 0
500 500 500 500 500 500 500 160 100 60 120 80 20 1000 20 20 20 5 5
5
[0030] The samples reduce and control the hydrogen sulfide level.
Sample 1 has comparable results to CE-1 and CE-3. However, Sample 1
can be removed in a aqueous phase and does not generate amines like
the triazine samples will.
Example 3
[0031] 5 g of H.sub.2S was bubbled into a 2 L flask containing 1 L
of a commercially available raw crude sample containing <25
.mu.g/ml of hydrogen sulfide initially. The flask was equipped with
a mechanical stirrer and a condenser with a caustic trap. The crude
oil was stirred at room temperature for 1 hour. The H.sub.2S
concentration in the H.sub.2S-infused crude was 3940 .mu.g/ml.
[0032] A demulsifier was added to the H.sub.2S-infused crude oil in
the amounts shown in Table 3.
[0033] 5% by volume wash water was mixed with glyoxal and
cocoalkyldimethylbenzyl ammonium chloride, as shown in Table 3, and
added to the H.sub.2S-infused crude oil. The wash water was mixed
with the H.sub.2S-infused crude oil at 4000 rpm for 2 seconds,
grids on, and heated to 130.degree. C. at a pressure of 4 psi to
form an emulsion.
[0034] The emulsion was allowed to sit for 32 minutes to separate
the water phase from the crude oil. A water drop reading was
performed to test the emulsion separation and is shown in Table 4.
The water phase was removed from the separated emulsion and
observed for clarity as shown in Table 3.
TABLE-US-00003 TABLE 3 Demulsifier.sup.1 Treatmeny.sup.3 Mean Water
Drop Separated Sample (ppm).sup.2 (ppm).sup.2 (ml) water Clarity
Blank 0 0 2.73 Clear CE-8 6 0 4.50 Clear 2 6 100 4.50 Slightly
cloudy 3 12 100 4.48 Slightly cloudy 4 6 250 4.75 Cloudy 5 12 250
4.70 Cloudy 6 6 500 4.75 Cloudy 7 12 500 4.75 Cloudy
.sup.1Demulsifier is an alkoxylated alkylphenol formaldehyde
available commercially from General Electric Company. .sup.2Doses
based on 100 ml total volume. .sup.3Treatment is glyoxal and
cocoalkyldimethylbenzyl ammonium chloride at 1.6% by weight
treatment level (actives basis) based on the weight of the
glyoxal.
TABLE-US-00004 TABLE 4 Water Drop Reading in ml 1 min 2 min 4 min 8
min 16 min 32 min Mean water Sample (ml) (ml) (ml) (ml) (ml) (ml)
drop (ml) Blank 0.4 1.8 2.7 3.5 4 4 2.73 CE-8 1.8 4 4.7 5.5 5.5 5.5
4.50 2 1.8 4 4.7 5.5 5.5 5.5 4.50 3 2 4 4.7 5.2 5.5 5.5 4.48 4 3 4
5 5.5 5.5 5.5 4.75 5 3 4 4.7 5.5 5.5 5.5 4.70 6 3 4 5 5.5 5.5 5.5
4.75 7 3 4 5 5.5 5.5 5.5 4.75
[0035] The increasing cloudiness in the separated water at higher
levels of hydrogen sulfide treatment indicates the presence of
captured hydrogen sulfide products that were removed with the
water. Also, the hydrogen sulfide scavenger does not negatively
impact the separation of the emulsion.
[0036] While typical embodiments have been set forth for the
purpose of illustration, the foregoing descriptions should not be
deemed to be a limitation on the scope herein. Accordingly, various
modifications, adaptations and alternatives may occur to one
skilled in the art without departing from the spirit and scope
herein.
* * * * *